1. Field of the Invention
The present invention generally relates to semiconductor substrate processing. More specifically, the present invention relates to a method and apparatus for performing limited area spectral analysis to monitor a semiconductor substrate process.
2. Description of the Related Art
Integrated circuits have evolved into complex devices that can include millions of components (e.g., transistors, capacitors, resistors, and the like) on a single chip. The evolution of chip designs continually requires faster circuitry and greater circuit density. The demands for greater circuit density necessitate a reduction in the dimensions of the integrated circuit components. The minimal dimensions of features of such devices are commonly referred to in the art as critical dimensions. The critical dimensions generally include the minimal widths of the features, such as lines, columns, openings, spaces between the lines, and the like.
As these critical dimensions shrink, accurate measurement and process control becomes more difficult. For example, one problem associated with a conventional plasma etch process used in the manufacture of integrated circuits is the lack of an ability to accurately monitor the formation of small features on the substrate and thereby accurately monitoring or predicting the endpoint for the etch process. This deficiency leads to lower yields and higher costs of manufacturing such devices.
Therefore, there is a need in the art for an improved method and apparatus for substrate monitoring and process control during the manufacture of integrated circuits.